1. Field of the Invention
This invention relates to a process for producing adducts of an ethylene-.alpha., .beta.-dicarboxyl compound with a butadiene oligomer or co-oligomer.
2. Description of the Prior Art
In order to use a resin as a film-forming material for water-based coatings, it is necessary to introduce generally hydrophilic groups such as carboxyl, hydroxyl, ether, amino, sulfonic acid and the like groups into the molecular structure of the resin. As a method for introducing carboxyl groups as hydrophilic groups into, for example, either drying oils containing conjugated double bonds such as tung oil, dehydrated castor oil, isomerized oil and the like, or drying oils containing non-conjugated double bonds such as linseed oil, soybean oil and the like, there is a method in which maleic anhydride is subjected to an addition reaction with respect to the above described drying oils, and the reaction product is then neutralized by the use of an alkali. These resulting products are widely used as malenized oil.
On one hand, it is well known to produce an adduct by treating thermally a butadiene oligomer or co-oligomer together with ethylene-.alpha., .beta.-dicarboxyl compound likewise in a method for introducing carboxyl groups into the butadiene oligomer or co-oligomer (Japanese Patent Publication No. 954/1971).
However, the adducts of a butadiene oligomer or co-oligomer with a ethylene-.alpha., .beta.-dicarboxyl compound exhibit remarkably increased viscosity during the addition reaction in comparison with these raw material polymers, and sometimes there is a case where the adducts develop into a gel. Furthermore, when an adduct has so excessively high viscosity, its water-solubilizing treatment becomes very difficult.
Accordingly, as a technically improved method to decrease viscosity of such adducts in a conventional production of the adducts of an ethylene-.alpha., .beta.-dicarboxyl compound with a butadiene oligomer or co-oligomer, it is well known to use a non-coloring stabilizer (French Patent No. 1332596), copper or a copper compound (Japanese Patent Publication Nos. 26870/1968 and 44557/1972), and an amine compound (West German Patent No. 2147639) as an anti-gelling agent for charge stock, respectively.
However, such non-coloring stabilizers those described in French Patent No. 1332596 such as tertiary amylhydroquinone, hydroquinone, diphenylamine, 2, 6-di-tert-4-methylphenol and the like involve such disadvantages that either air-drying of resulting coatings is significantly prevented or it is remarkably retarded even if such a stabilizer is added in a very small amount in case of a certain type of butadiene oligomer, and that the effect for reducing viscosity of adducts is poor in general.
Furthermore, when copper and copper compounds described in Japanese Patent Publication Nos. 26870/1968 and 44557/1972 are used, there are such disadvantages that the resulting adducts are remarkably colored, besides the rate of addition reaction being delayed, and that there is also a comparatively poor effect for decreasing viscosity of the adducts.
Still further, when amine compounds those described in West German Patent No. 2147639 are used, there are such disadvantages that the resulting adducts are remarkably colored, and in addition a scarce addition reaction arises at elevated temperatures in the vicinity of 200.degree. C., and maleic anhydride reacts with such amine compound so that it produces by-products.
In addition, there is described in Japanese Patent Laid-open No. 83795/1974 that when a phenylenediamine derivative is employed, an adduct of low viscosity and having a good hue is obtained. It is, however, still desired to, attain much more improvement in the invention disclosed.